Returns

Revokes access given to the current application. Future sign-in attempts will
require the user to re-consent to all requested scopes. Applications are required to
provide users that are signed in with Google the ability to disconnect their Google
account from the app. If the user deletes their account, you must delete the
information that your app obtained from the Google APIs.

The GoogleSignInAccount will possibly contain an ID token which may be used to
authenticate and identify sessions that you establish with your application servers. If
you use the ID token expiry time to determine your session lifetime, you should
retrieve a refreshed ID token, by calling silentSignIn prior to each API call to your
application server.

Calling silentSignIn can also help you detect user revocation of access to your
application on other platforms and you can call
getSignInIntent() again to ask the user to re-authorize.

If your user has never previously signed in to your app on the current device, we
can still try to sign them in, without displaying user interface, if they have signed
in on a different device.

We attempt to sign users in if:

There is one and only one matching account on the device that has previously
signed in to your application, and

the user previously granted all of the scopes your app is requesting for this
sign in.